10 USMLE Pharmacology Quick Review Questions with Answers (Set 43)

These 10 quick USMLE pharmacology review questions test high-yield facts that show up again and again on the exam, including Phenoxybenzamine, Methylene blue, Lupus-like syndrome, Alpha-blocker, Buprenorphine. Each question includes the correct answer.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.

Questions

Question 1. A 30-year-old woman presents with episodic palpitations, sweating, and headaches. Her blood pressure is persistently elevated. Laboratory evaluation shows elevated plasma catecholamines. MRI of the abdomen reveals an adrenal mass. Which of the following is the best initial preoperative management?

A- Clonidine
B- Labetalol
C- Phenoxybenzamine
D- Propranolol

C- Phenoxybenzamine- In pheochromocytoma, alpha-blockade with phenoxybenzamine is required before any beta-blockade. Giving beta-blockers first, such as propranolol, can precipitate a hypertensive crisis due to unopposed alpha stimulation.
The correct answer is C

 

Question 2. Topical benzocaine overuse can cause sudden cyanosis with normal PaO₂. Which one of the following substances can reverse this reaction?

A- Atropine
B- Methylene blue
C- Naloxone
D- Sodium bicarbonate

B- Methylene blue- This is a case of methemoglobinemia from oxidizing agents such as benzocaine or dapsone. Methylene blue is the most effective treatment.
The correct answer is B

 

Question 3. A 32-year-old woman with a history of migraines is prescribed sumatriptan. What is its mechanism of action?

A- 5-HT1B/1D receptor agonist
B- 5-HT2 receptor antagonist
C- Dopamine receptor antagonist
D- Voltage-gated calcium channel blocker

A- 5-HT1B/1D receptor agonist- Sumatriptan activates serotonin 5-HT1B/1D receptors, causing vasoconstriction and inhibiting trigeminal nerve activation.
The correct answer is A

 

Question 4. A 70-year-old man with atrial fibrillation is prescribed apixaban. What is its mechanism of action?

A- Direct factor IIa (thrombin) inhibitor
B- Direct factor Xa inhibitor
C- Indirect factor Xa inhibitor via antithrombin III
D- Vitamin K epoxide reductase inhibitor

B- Direct factor Xa inhibitor- Apixaban and rivaroxaban directly inhibit factor Xa, reducing thrombin generation and clot formation.
The correct answer is B

 

Question 5. A 25-year-old man is treated with chloramphenicol for typhoid fever. He later develops pallor, fatigue, and pancytopenia. Which adverse effect best explains this presentation?

A- Dose-dependent reversible anemia
B- Folate deficiency
C- Irreversible aplastic anemia
D- Vitamin B12 deficiency

C- Irreversible aplastic anemia- Chloramphenicol can rarely cause dose-independent, irreversible aplastic anemia, distinct from its reversible anemia caused by mitochondrial protein synthesis inhibition.
The correct answer is C

 

Question 6. A 60-year-old woman with hypertension is prescribed hydralazine. Which adverse effect is most characteristically associated with this drug?

A- Gingival hyperplasia
B- Lupus-like syndrome
C- Pulmonary fibrosis
D- Tendon rupture

B- Lupus-like syndrome- Hydralazine, procainamide, and isoniazid are classically linked with drug-induced lupus.
The correct answer is B

 

Question 7. A 19-year-old college student with meningitis is treated with ceftriaxone. What is the mechanism of action of this drug?

A- Disruption of bacterial cell membrane
B- Inhibition of peptidoglycan cross-linking
C- Inhibition of protein synthesis at the 50S ribosomal subunit
D- Inhibition of transpeptidase enzymes (penicillin-binding proteins)

D- Inhibition of transpeptidase enzymes (penicillin-binding proteins)- β-lactam antibiotics (penicillins, cephalosporins, carbapenems) bind PBPs, preventing cross-linking of peptidoglycan → bactericidal.
The correct answer is D

 

Question 8. A 35-year-old man presents with palpitations, sweating, and episodic headaches. Blood pressure is persistently high. Urinary catecholamines and metanephrines are elevated. Which of the following is the best initial management before surgery?

A- ACE inhibitor
B- Alpha-blocker
C- Beta-blocker
D- Calcium channel blocker

B- Alpha-blocker- In pheochromocytoma, alpha-blockade (phenoxybenzamine) must be given before beta-blockade to prevent hypertensive crisis.
The correct answer is B

 

Question 9. A patient who was involved in a motor vehicle accident 2 years ago now has chronic pain. He tells his doctor he thinks he is becoming addicted to his short-acting morphine. He has been visiting multiple physicians to obtain prescription refills. Which of the following is the most appropriate treatment for his opioid use disorder?

A- Acamprosate
B- Buprenorphine
C- Naltrexone
D- Varenicline

B- Buprenorphine- Buprenorphine is a partial opioid agonist used as first-line therapy for opioid use disorder. It helps reduce cravings and withdrawal symptoms.
Acamprosate is for alcohol dependence.
Naltrexone can be used for opioid dependence, but only after detoxification.
Varenicline is used for smoking cessation.
The correct answer is B

 

Question 10. A 65-year-old man with heart failure is started on spironolactone. Which adverse effect should be monitored most closely?

A- Gynecomastia
B- Hypocalcemia
C- Hypokalemia
D- Metabolic acidosis

A- Gynecomastia- Spironolactone is an aldosterone antagonist with antiandrogen effects that can cause gynecomastia and hyperkalemia.
The correct answer is A

 

High-yield points from this set

  • In pheochromocytoma, alpha-blockade with phenoxybenzamine is required before any beta-blockade.
  • This is a case of methemoglobinemia from oxidizing agents such as benzocaine or dapsone.
  • HT1B/1D receptor agonist- Sumatriptan activates serotonin 5-HT1B/1D receptors, causing vasoconstriction and inhibiting trigeminal nerve activation.
  • Apixaban and rivaroxaban directly inhibit factor Xa, reducing thrombin generation and clot formation.
  • Chloramphenicol can rarely cause dose-independent, irreversible aplastic anemia, distinct from its reversible anemia caused by mitochondrial protein synthesis inhibition.

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